This invention relates to a weft feeler device of a loom, particularly a weft feeler device of a loom capable of detecting a success or a failure of an insertion of the weft when so-called double wefts insertion is carried out in a jet loom.
In the jet loom, two wefts per one pick are inserted to enable its productivity to be substantially improved and this operating form is generally called a double wefts insertion process. In this operation, the wefts are inserted through one weft insertion nozzle or parallelly arranged two weft insertion nozzles which are concurrently operated (for example, refer to Japanese Patent Application Laid-Open No. Sho 61-646).
When such double wefts are inserted, it is necessary to make a special arrangement for a weft feeler for detecting a success or a failure of the two wefts insertion. That is, the weft feeler is required to make a positive sensing of both cases in which both inserted wefts are both failured to insert and only one of them is failured. The prior art weft feeler merely detects a presence or a non-presence of the weft and it may not perform the latter sensing operation. Because, in case of the weft feeler using a photo-electrical sensor, when the two wefts are overlapped to each other, it is almost impossible to detect that the wefts are two or only one weft is present even if the presence or non presence of the weft be sensed.
In view of the foregoing, it has been proposed as a weft sensing method adapted for the double wefts insertion, to make a positive delay in reaching times of the two wefts to be inserted or to retract one weft from a sensing region of a photo-electrical sensor so as to perform a respective and discrete checking of the two wefts one by one. (refer to Japanese Patent Application Laid-Open No. Hei 2-19550, 2-26963 and 2-33356, respectively).
For example, when the two wefts to be released from each separate weft measuring and storing devices are to be inserted, only a terminal end portion of one weft is delayed to reach a sensing region of the sensor in time from the other weft by using an auxiliary engaging pin, thereby the sensor can check at first a presence or a non-presence of the other weft. Then, the auxiliary engaging pin is operated to cause the delayed one weft to be inserted into a normal length and at the same time the weft already checked at first is mechanically pulled back by a suitable pulling-back mechanism or the like and retracted from the sensing region of the sensor, resulting in that only the delayed weft can be singularly checked. That is, since the sensor may separately check the inserted two wefts in a separated time interval, it is possible to make a positive detecting of the success or failure of the double wefts.
In accordance with the prior art described above, although it has an advantage that a photo-electrical sensor can be used as a former one, it has a disadvantage that the auxiliary pin for delaying a reaching time of one weft or an auxiliary mechanism member such as the pulling-back mechanism for retracting the other weft is required not only to cause an entire structure to be complicated but also the system not to be adaptable for a high-speed operation. In addition, the prior art has a problem that the inserted two wefts are frequently entangled to each other under an influence of twisting or the like, the weft insertion to the sensing region for the delayed weft or the pulling-back operation for the other weft is not smoothly carried out, so the operation is not positively performed.